a11y: accessibility overhaul

[OEvgeny]

List of ADO issues fixed:

• Bug 79098: [Visual Requirements - Bot Framework Emulator - Welcome]: Luminosity ratio of links present on the 'Welcome' screen with surrounding text is less than required 3:1.
• Bug 79099: [Supporting the Platform - Bot Framework Emulator - JSON]: Luminosity ratio of text present on the 'JSON Section' with background is less than required 4.5:1 ratio.
• Bug 79121: [Usable - Bot Framework Emulator - Welcome]: Buttons 'Sign in with your Azure account' & 'Create a new bot configuration' are visually appearing as links on the 'Welcome' screen.
• Bug 79147: [Keyboard Navigation - Bot Framework Emulator - Emulator Settings]: Upon selecting any control present under 'Emulator Settings' whether checkboxes or edit fields, keyboard focus suddenly moves to the first edit field of the screen.
• Bug 79150: [Screen Reader - Bot Framework Emulator - Emulator Settings]: Screen reader is not announcing the associated label 'User Settings', 'Application Updates', 'Data Collection' while navigating the checkboxes.
• Bug 79151: [Usable - Bot Framework Emulator - Welcome]: Buttons 'Sign in with your Azure account' & 'Create a new bot configuration' are visually appearing as links on the 'Welcome' screen.
• Bug 79153: [Keyboard Navigation - Bot Framework Emulator - Emulator Settings]: Upon selecting any control present under 'Emulator Settings' whether checkboxes or edit fields, keyboard focus suddenly moves to the first edit field of the screen.
• Bug 79156: [Supporting the Platform - Bot Framework Emulator - System High Contrast]: After applying system high contrast, application is not adapting its own high contrast themes.
• Bug 79157: [Visual Requirements - Bot Framework Emulator - Welcome]: Luminosity ratio of links present on the 'Welcome' screen with surrounding text is less than required 3:1.
• Bug 79158: [Screen Reader - Bot Framework Emulator - Live Chat bot Screen]: Voice Over announces unnecessary information as tick box on Chats present under 'Live Chat bot' tab.
• Bug 79159: [Supporting the Platform - Bot Framework Emulator - JSON]: Luminosity ratio of text present on the 'JSON Section' with background is less than required 4.5:1 ratio.
• Bug 79160: [Usable - Bot Framework Emulator - Welcome]: 'Sign in with your Azure account' & 'Create a new bot configuration' buttons are visually appearing as links on the 'Welcome' screen.
• Bug 79169: [Keyboard Navigation - Bot Framework Emulator - Emulator Settings]: Upon selecting any control present under 'Emulator Settings' whether checkboxes or edit fields, keyboard focus suddenly moves to the first edit field of the screen.
• Bug 79170: [Screen Reader - Bot Framework Emulator - Emulator Settings]: Screen reader is not announcing the associated label 'User Settings', 'Application Updates', 'Data Collection' while navigating the checkboxes.
• Bug 79173: [Usable - Bot Framework Emulator - Menu Bar]: Voice Over does not announce the count for the menu items present in the Menu bar header.
• Bug 79175: [Screen Reader - Bot Framework Emulator - Emulator Settings]: Voice Over is not announcing the associated label 'User Settings', 'Application Updates', 'Data Collection' while navigating the checkboxes.
• Bug 79176: [Screen Reader - Bot Framework Emulator - Create a new bot configuration]: Voice Over does not announce 'Show' button information on activating 'Hide' button.
• Bug 79179: [Screen Reader - Bot Framework Emulator - Chat bot Screen]: Voice Over is announcing different label than the visually defined label for the 'Restart conversation from here' button.
• Bug 79180: [Supporting the Platform - Bot Framework Emulator - JSON]: Luminosity ratio of text present on the 'JSON Section' with background is less than required 4.5:1 ratio.
• Bug 79182: [Visual Requirements - Bot Framework Emulator -Restart conversation]: The Luminosity ratio of menu item ('^') is 2:1 which is less than 3:1.
• Bug 79184: [Keyboard Navigation - Bot Framework Emulator -check for updates]: Keyboard focus doesn't retain to 'help' menu after invoking cancel button under update available dialog.

[coveralls]

coverage: 67.629% (-0.06%) from 67.693% when pulling 9898eb20350df4466c87060688d5bf327d37aac6 on OEvgeny:a11y/overhaul into b6c7dcc61105723c8e238620557b0d8160d2b0f2 on microsoft:main.

[OEvgeny]

/azp run

[azure-pipelines[bot]]

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